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편집 파일: shrinker.h

/* SPDX-License-Identifier: GPL-2.0 */ #ifndef _LINUX_SHRINKER_H #define _LINUX_SHRINKER_H #include <linux/atomic.h> #include <linux/types.h> #include <linux/rh_kabi.h> /* * This struct is used to pass information from page reclaim to the shrinkers. * We consolidate the values for easier extension later. * * The 'gfpmask' refers to the allocation we are currently trying to * fulfil. */ struct shrink_control { gfp_t gfp_mask; /* current node being shrunk (for NUMA aware shrinkers) */ int nid; /* * How many objects scan_objects should scan and try to reclaim. * This is reset before every call, so it is safe for callees * to modify. */ unsigned long nr_to_scan; /* * How many objects did scan_objects process? * This defaults to nr_to_scan before every call, but the callee * should track its actual progress. */ unsigned long nr_scanned; /* current memcg being shrunk (for memcg aware shrinkers) */ RH_KABI_EXCLUDE(struct mem_cgroup *memcg) }; #define SHRINK_STOP (~0UL) #define SHRINK_EMPTY (~0UL - 1) /* * A callback you can register to apply pressure to ageable caches. * * @count_objects should return the number of freeable items in the cache. If * there are no objects to free, it should return SHRINK_EMPTY, while 0 is * returned in cases of the number of freeable items cannot be determined * or shrinker should skip this cache for this time (e.g., their number * is below shrinkable limit). No deadlock checks should be done during the * count callback - the shrinker relies on aggregating scan counts that couldn't * be executed due to potential deadlocks to be run at a later call when the * deadlock condition is no longer pending. * * @scan_objects will only be called if @count_objects returned a non-zero * value for the number of freeable objects. The callout should scan the cache * and attempt to free items from the cache. It should then return the number * of objects freed during the scan, or SHRINK_STOP if progress cannot be made * due to potential deadlocks. If SHRINK_STOP is returned, then no further * attempts to call the @scan_objects will be made from the current reclaim * context. * * @flags determine the shrinker abilities, like numa awareness */ struct shrinker { unsigned long (*count_objects)(struct shrinker *, struct shrink_control *sc); unsigned long (*scan_objects)(struct shrinker *, struct shrink_control *sc); long batch; /* reclaim batch size, 0 = default */ int seeks; /* seeks to recreate an obj */ unsigned flags; void *private_data; /* These are for internal use */ struct list_head list; #ifdef CONFIG_MEMCG /* ID in shrinker_idr */ int id; #endif #ifdef CONFIG_SHRINKER_DEBUG int debugfs_id; const char *name; struct dentry *debugfs_entry; #endif /* objs pending delete, per node */ atomic_long_t *nr_deferred; RH_KABI_RESERVE(1) RH_KABI_RESERVE(2) }; #define DEFAULT_SEEKS 2 /* A good number if you don't know better. */ /* Internal flags */ #define SHRINKER_REGISTERED BIT(0) #define SHRINKER_ALLOCATED BIT(1) /* Flags for users to use */ #define SHRINKER_NUMA_AWARE BIT(2) #define SHRINKER_MEMCG_AWARE BIT(3) /* * It just makes sense when the shrinker is also MEMCG_AWARE for now, * non-MEMCG_AWARE shrinker should not have this flag set. */ #define SHRINKER_NONSLAB BIT(4) __printf(2, 3) struct shrinker *shrinker_alloc(unsigned int flags, const char *fmt, ...); void shrinker_register(struct shrinker *shrinker); void shrinker_free(struct shrinker *shrinker); extern int __printf(2, 3) prealloc_shrinker(struct shrinker *shrinker, const char *fmt, ...); extern void register_shrinker_prepared(struct shrinker *shrinker); extern int __printf(2, 3) register_shrinker(struct shrinker *shrinker, const char *fmt, ...); extern void unregister_shrinker(struct shrinker *shrinker); extern void free_prealloced_shrinker(struct shrinker *shrinker); extern void synchronize_shrinkers(void); #ifdef CONFIG_SHRINKER_DEBUG extern int __printf(2, 3) shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...); #else /* CONFIG_SHRINKER_DEBUG */ static inline __printf(2, 3) int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) { return 0; } #endif /* CONFIG_SHRINKER_DEBUG */ #endif /* _LINUX_SHRINKER_H */